Various configurations and models of liquid dispensers, particularly liquid soap dispensers, are well known in the art. Conventional dispensers employed in public restrooms and the like are wall mounted units that typically include a house or structure that is permanently affixed to a wall. These dispensers usually include an access door or member so that the dispenser can be opened by a maintenance person for refilling or servicing. With certain types of dispensers, separate refill cartridges are inserted into the housing structure. With other types of dispensers, the maintenance technician must directly refill a reservoir provided in the housing structure. The dispensers typically include a delivery device, such as a dosing pump, and a device such as a lever or button for actuating the dosing pump. The dispensers may be vented or unvented.
Improved dispensers particularly suited for use as soap dispensers are described in detail in the following U.S. Pat. Nos. 6,533,145; 6,543,651; 6,575,334; and 6,575,335.
In various environments and uses of dispensers, it is often desirable to convert and dispense the liquid stored in a dispenser as a foam. Foam is often preferred by the consumer and less of the liquid is needed per measured dose of foam, thus extending the time between refill or replacement of the dispenser. Foaming pumps are know in the art for this purpose, and typically work by mixing the liquid with air and forcing the mixture through a separator, such as a screen. For various reasons, however, such foaming pump mechanisms have not been widely used or incorporated with relatively large volume dispensers of the type preferred for use in public restrooms, and the like.
The present invention provides an improvement to the type of viscous liquid dispensers described in the U.S. patents cited above, and particularly provides an internal foaming pump mechanism with such dispensers.